1. Field of Invention
The present invention relates to an improved fused closure for a plastic bag and an apparatus for effecting the closure. The closure consists of a randomly gathered throat portion of a plastic bag being fused together by at least two or more spaced apart rows of heat conductive needles penetrated in the throat portion.
2. Description of Prior Art
The open ends of many plastic bags are usually sealed by gathering a portion of the bag and placing a twist wire about the gathered throad portion or else applying a removable securement tab or the like elements. A disadvantage of such closure elements is that they are often not properly secured to the bag and become easily undone. Also such elements require special machinery for application thereof to a filled bag throat portion. Further, it is often necessary to stop the bagging machinery whereby to correct a malfunction in such wire or tab applicator or to load the applicator with closure tapes or tabs. Such applicator devices are also time and labor consuming and often require adjustment or repair when parts becomes defective or worn. Most prior art closure devices are also not tamper-proof and can easily be removed from such bags.
The present invention overcomes the above-mentioned disadvantages by providing a novel seal for a plastic bag wherein the throat portion is heat sealed by the use of heated penetrating needles. In the prior art, it is known to heat seal a plastic bag by the use of heated penetrating needles. Reference is made to U.K. Pat. No. 2034278 which discloses a method and apparatus for effecting this type heat seal. However, the disadvantage of that method and apparatus is that the plastic bag must be oriented vertically so as to have its open end in an erect position, and it is then necessary to fold this open end portion of the bag into a specific zig-zag fashion before the bag is pierced with warm needles. This is often difficult with a product in the bag. This is also time consuming and still does not provide a weld seam which is rigid and which does not become accidentally undone. In order to solve this problem, the Patentee has proposed folding over the upper end of the bag before the heat seal is made, and this again makes the process even more time consuming, difficult and expensive.